1. Field of the Invention
Present invention relates to an optical measuring system and an optical measuring method.
In particular, the measuring system and the measuring method can be used for examining a retina of an eye of a patient, and for creating a data set, from which images of the retina can be created. The data set can, in particular, be two-dimensional or three-dimensional.
2. Brief Description of Related Art
From U.S. Pat. No. 5,321,501, an optical measuring system for the examination of a retina of an eye is known. The disclosure of this document is fully incorporated by reference into the present application.
From pages 29 and 30 of the Program Year 2 of the Annual Report of the National Science Foundation, Center for Adaptive Optics, University of California, Santa Cruz, Calif., a retina camera is known, which is subsequently discussed in conjunction with FIG. 1.
The camera 1 serves to take images of a retina 3 of an eye 5 of a patient. The camera 1 operates according to an OCT-method, wherein OCT stands for “Optical Coherence Tomography”. Two light sources 7 and 9 are provided for selectively or together creating a source beam 11, which is divided into an object illuminating beam 15 and a reference beam 17 by a first beam splitter 13. The reference beam 17 is reflected back into itself at an actuator-mirror-unit 19, wherein an optical path length of the reference beam between the beam splitter 13 and its reflection at the actuator-mirror-unit 19 is variable via an actuator of the unit 19. The object illuminating beam 15 is focussed onto the retina 3 by a lens 21 of the eye 5, and light of the object illuminating beam reflected or scattered back from the retina 3 is again incident on the beam splitter 13 and is transmitted therethrough. The light of the reference beam reflected off the actuator-mirror-unit 19 is reflected at the beam splitter 13 and is superimposed with the light coming back from the retina, to form a common light beam 22. The light beam 22 is directed via lenses 25 to an active optical element 27 and reflected therefrom. The reflected beam 22 is directed via a further lens 29 and a mirror 30 to a second beam splitter 33. The beam splitter 33 divides beam 22 into an OCT measuring beam 35 and a wavefront measuring beam 37. The OCT measuring beam 35 is directed via lenses 39 onto a camera 49, which obtains OCT measuring data from a depth of the retina 3 set by actuating the actuator-mirror-unit 19.
The wavefront measuring beam 37 is directed to a Hartmann-Shack wavefront sensor 41 via a lens 39, to detect wavefronts in the beam 22. The active optical element 27 is actuated in dependence of the detected wavefronts in order to improve on a quality of the OCT images obtained by the detector 49.
It has been found that this conventional system does not fulfill expectations with regard to its imaging quality, in particular with respect to its lateral and depth resolution.